There exists an electric power converter with a semiconductor module that has a switching element therein, and a cooling pipe that cools the semiconductor module as the electric power converter installed in an electric vehicle, a hybrid car, etc., for example.
In the electric power converter, a structure of disposing a flat spring member that urges a piled unit of the semiconductor module and the cooler together in the piling direction is proposed (refer to Japanese Patent Application Laid-Open Publication No. 2011-103728, for example).
Thereby, while fully securing a contact pressure between the semiconductor module and the cooling pipes, a dimensional tolerance of the piled unit in the piling direction can be absorbed by the flat spring member.
Moreover, a change of the contact pressure caused by a dimensional change of the piled unit accompanying a temperature change is prevented by providing the flat spring member.
However, providing the flat spring member as mentioned above will cause an increase in a number of parts, and will cause problems such as enlargement of the electric power converter, and an increase in manufacturing steps.
Moreover, in order to absorb the dimensional tolerance and thermal expansion of the piled unit by the flat spring member as mentioned above, a spring constant of the flat spring member needs to be below a predetermined value, and it is necessary to enlarge the size of the flat spring member in a pressurizing direction.
As a result, there is a possibility that the electric power converter becomes large.
On the other hand, if the thickness of the flat spring member is simply made small in order to make the spring constant small, the strength of the flat spring member will be reduced.